git.sesse.net Git - ffmpeg/blob - libavcodec/w32pthreads.h

   1 /*
   2  * Copyright (C) 2010-2011 x264 project
   3  *
   4  * Authors: Steven Walters <kemuri9@gmail.com>
   5  *          Pegasys Inc. <http://www.pegasys-inc.com>
   6  *
   7  * This file is part of Libav.
   8  *
   9  * Libav is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * Libav is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with Libav; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 /**
  25  * @file
  26  * w32threads to pthreads wrapper
  27  */
  28
  29 #ifndef AVCODEC_W32PTHREADS_H
  30 #define AVCODEC_W32PTHREADS_H
  31
  32 /* Build up a pthread-like API using underlying Windows API. Have only static
  33  * methods so as to not conflict with a potentially linked in pthread-win32
  34  * library.
  35  * As most functions here are used without checking return values,
  36  * only implement return values as necessary. */
  37
  38 #define WIN32_LEAN_AND_MEAN
  39 #include <windows.h>
  40 #include <process.h>
  41
  42 #include "libavutil/common.h"
  43
  44 typedef struct {
  45     void *handle;
  46     void *(*func)(void* arg);
  47     void *arg;
  48     void *ret;
  49 } pthread_t;
  50
  51 /* the conditional variable api for windows 6.0+ uses critical sections and
  52  * not mutexes */
  53 typedef CRITICAL_SECTION pthread_mutex_t;
  54
  55 /* This is the CONDITIONAL_VARIABLE typedef for using Window's native
  56  * conditional variables on kernels 6.0+.
  57  * MinGW does not currently have this typedef. */
  58 typedef struct {
  59     void *ptr;
  60 } pthread_cond_t;
  61
  62 /* function pointers to conditional variable API on windows 6.0+ kernels */
  63 static void (WINAPI *cond_broadcast)(pthread_cond_t *cond);
  64 static void (WINAPI *cond_init)(pthread_cond_t *cond);
  65 static void (WINAPI *cond_signal)(pthread_cond_t *cond);
  66 static BOOL (WINAPI *cond_wait)(pthread_cond_t *cond, pthread_mutex_t *mutex,
  67                                 DWORD milliseconds);
  68
  69 static unsigned __stdcall attribute_align_arg win32thread_worker(void *arg)
  70 {
  71     pthread_t *h = arg;
  72     h->ret = h->func(h->arg);
  73     return 0;
  74 }
  75
  76 static int pthread_create(pthread_t *thread, const void *unused_attr,
  77                           void *(*start_routine)(void*), void *arg)
  78 {
  79     thread->func   = start_routine;
  80     thread->arg    = arg;
  81     thread->handle = (void*)_beginthreadex(NULL, 0, win32thread_worker, thread,
  82                                            0, NULL);
  83     return !thread->handle;
  84 }
  85
  86 static void pthread_join(pthread_t thread, void **value_ptr)
  87 {
  88     DWORD ret = WaitForSingleObject(thread.handle, INFINITE);
  89     if (ret != WAIT_OBJECT_0)
  90         return;
  91     if (value_ptr)
  92         *value_ptr = thread.ret;
  93     CloseHandle(thread.handle);
  94 }
  95
  96 static inline int pthread_mutex_init(pthread_mutex_t *m, void* attr)
  97 {
  98     InitializeCriticalSection(m);
  99     return 0;
 100 }
 101 static inline int pthread_mutex_destroy(pthread_mutex_t *m)
 102 {
 103     DeleteCriticalSection(m);
 104     return 0;
 105 }
 106 static inline int pthread_mutex_lock(pthread_mutex_t *m)
 107 {
 108     EnterCriticalSection(m);
 109     return 0;
 110 }
 111 static inline int pthread_mutex_unlock(pthread_mutex_t *m)
 112 {
 113     LeaveCriticalSection(m);
 114     return 0;
 115 }
 116
 117 /* for pre-Windows 6.0 platforms we need to define and use our own condition
 118  * variable and api */
 119 typedef struct {
 120     pthread_mutex_t mtx_broadcast;
 121     pthread_mutex_t mtx_waiter_count;
 122     volatile int waiter_count;
 123     HANDLE semaphore;
 124     HANDLE waiters_done;
 125     volatile int is_broadcast;
 126 } win32_cond_t;
 127
 128 static void pthread_cond_init(pthread_cond_t *cond, const void *unused_attr)
 129 {
 130     win32_cond_t *win32_cond = NULL;
 131     if (cond_init) {
 132         cond_init(cond);
 133         return;
 134     }
 135
 136     /* non native condition variables */
 137     win32_cond = av_mallocz(sizeof(win32_cond_t));
 138     if (!win32_cond)
 139         return;
 140     cond->ptr = win32_cond;
 141     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
 142     if (!win32_cond->semaphore)
 143         return;
 144     win32_cond->waiters_done = CreateEvent(NULL, TRUE, FALSE, NULL);
 145     if (!win32_cond->waiters_done)
 146         return;
 147
 148     pthread_mutex_init(&win32_cond->mtx_waiter_count, NULL);
 149     pthread_mutex_init(&win32_cond->mtx_broadcast, NULL);
 150 }
 151
 152 static void pthread_cond_destroy(pthread_cond_t *cond)
 153 {
 154     win32_cond_t *win32_cond = cond->ptr;
 155     /* native condition variables do not destroy */
 156     if (cond_init)
 157         return;
 158
 159     /* non native condition variables */
 160     CloseHandle(win32_cond->semaphore);
 161     CloseHandle(win32_cond->waiters_done);
 162     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
 163     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
 164     av_freep(&win32_cond);
 165     cond->ptr = NULL;
 166 }
 167
 168 static void pthread_cond_broadcast(pthread_cond_t *cond)
 169 {
 170     win32_cond_t *win32_cond = cond->ptr;
 171     int have_waiter;
 172
 173     if (cond_broadcast) {
 174         cond_broadcast(cond);
 175         return;
 176     }
 177
 178     /* non native condition variables */
 179     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 180     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 181     have_waiter = 0;
 182
 183     if (win32_cond->waiter_count) {
 184         win32_cond->is_broadcast = 1;
 185         have_waiter = 1;
 186     }
 187
 188     if (have_waiter) {
 189         ReleaseSemaphore(win32_cond->semaphore, win32_cond->waiter_count, NULL);
 190         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 191         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 192         ResetEvent(win32_cond->waiters_done);
 193         win32_cond->is_broadcast = 0;
 194     } else
 195         pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 196     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 197 }
 198
 199 static int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 200 {
 201     win32_cond_t *win32_cond = cond->ptr;
 202     int last_waiter;
 203     if (cond_wait) {
 204         cond_wait(cond, mutex, INFINITE);
 205         return 0;
 206     }
 207
 208     /* non native condition variables */
 209     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 210     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 211     win32_cond->waiter_count++;
 212     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 213     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 214
 215     // unlock the external mutex
 216     pthread_mutex_unlock(mutex);
 217     WaitForSingleObject(win32_cond->semaphore, INFINITE);
 218
 219     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 220     win32_cond->waiter_count--;
 221     last_waiter = !win32_cond->waiter_count || !win32_cond->is_broadcast;
 222     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 223
 224     if (last_waiter)
 225         SetEvent(win32_cond->waiters_done);
 226
 227     // lock the external mutex
 228     return pthread_mutex_lock(mutex);
 229 }
 230
 231 static void pthread_cond_signal(pthread_cond_t *cond)
 232 {
 233     win32_cond_t *win32_cond = cond->ptr;
 234     int have_waiter;
 235     if (cond_signal) {
 236         cond_signal(cond);
 237         return;
 238     }
 239
 240     pthread_mutex_lock(&win32_cond->mtx_broadcast);
 241
 242     /* non-native condition variables */
 243     pthread_mutex_lock(&win32_cond->mtx_waiter_count);
 244     have_waiter = win32_cond->waiter_count;
 245     pthread_mutex_unlock(&win32_cond->mtx_waiter_count);
 246
 247     if (have_waiter) {
 248         ReleaseSemaphore(win32_cond->semaphore, 1, NULL);
 249         WaitForSingleObject(win32_cond->waiters_done, INFINITE);
 250         ResetEvent(win32_cond->waiters_done);
 251     }
 252
 253     pthread_mutex_unlock(&win32_cond->mtx_broadcast);
 254 }
 255
 256 static void w32thread_init(void)
 257 {
 258     HANDLE kernel_dll = GetModuleHandle(TEXT("kernel32.dll"));
 259     /* if one is available, then they should all be available */
 260     cond_init      =
 261         (void*)GetProcAddress(kernel_dll, "InitializeConditionVariable");
 262     cond_broadcast =
 263         (void*)GetProcAddress(kernel_dll, "WakeAllConditionVariable");
 264     cond_signal    =
 265         (void*)GetProcAddress(kernel_dll, "WakeConditionVariable");
 266     cond_wait      =
 267         (void*)GetProcAddress(kernel_dll, "SleepConditionVariableCS");
 268 }
 269
 270 #endif /* AVCODEC_W32PTHREADS_H */